/** @file * IPRT - Memory Object Allocation Cache. */ /* * Copyright (C) 2006-2022 Oracle and/or its affiliates. * * This file is part of VirtualBox base platform packages, as * available from https://www.virtualbox.org. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation, in version 3 of the * License. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, see . * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included * in the VirtualBox distribution, in which case the provisions of the * CDDL are applicable instead of those of the GPL. * * You may elect to license modified versions of this file under the * terms and conditions of either the GPL or the CDDL or both. * * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 */ #ifndef IPRT_INCLUDED_memcache_h #define IPRT_INCLUDED_memcache_h #ifndef RT_WITHOUT_PRAGMA_ONCE # pragma once #endif #include #include RT_C_DECLS_BEGIN /** @defgroup grp_rt_memcache RTMemCache - Memory Object Allocation Cache * @ingroup grp_rt * * Optimized allocation, initialization, freeing and destruction of memory * objects of the same kind and size. Objects are constructed once, then * allocated and freed one or more times, until finally destructed together with * the cache (RTMemCacheDestroy). It's expected behavior, even when pfnCtor is * NULL, that the user will be store information that should be persistent * across RTMemCacheFree calls. * * The objects are zeroed prior to calling pfnCtor. For obvious reasons, the * objects are not touched by the cache after that, so that RTMemCacheAlloc will * return the object in the same state as when it as handed to RTMemCacheFree. * * @todo A callback for the reuse (at alloc time) might be of interest. * * @{ */ /** A memory cache handle. */ typedef R3R0PTRTYPE(struct RTMEMCACHEINT *) RTMEMCACHE; /** Pointer to a memory cache handle. */ typedef RTMEMCACHE *PRTMEMCACHE; /** Nil memory cache handle. */ #define NIL_RTMEMCACHE ((RTMEMCACHE)0) /** * Object constructor. * * This is called for when an element is allocated for the first time. * * @returns IPRT status code. * @param hMemCache The cache handle. * @param pvObj The memory object that should be initialized. * @param pvUser The user argument. * * @remarks No serialization is performed. */ typedef DECLCALLBACKTYPE(int, FNMEMCACHECTOR,(RTMEMCACHE hMemCache, void *pvObj, void *pvUser)); /** Pointer to an object constructor for the memory cache. */ typedef FNMEMCACHECTOR *PFNMEMCACHECTOR; /** * Object destructor. * * This is called when we're shrinking or destroying the cache. * * @param hMemCache The cache handle. * @param pvObj The memory object that should be initialized. * @param pvUser The user argument. * * @remarks No serialization is performed. */ typedef DECLCALLBACKTYPE(void, FNMEMCACHEDTOR,(RTMEMCACHE hMemCache, void *pvObj, void *pvUser)); /** Pointer to an object destructor for the memory cache. */ typedef FNMEMCACHEDTOR *PFNMEMCACHEDTOR; /** * Create an allocation cache for fixed size memory objects. * * @returns IPRT status code. * @param phMemCache Where to return the cache handle. * @param cbObject The size of one memory object. * @param cbAlignment The object alignment. This must be a power of * two. The higest alignment is 64. If set to 0, * a sensible alignment value will be derived from * the object size. * @param cMaxObjects The maximum cache size. Pass UINT32_MAX if unsure. * @param pfnCtor Object constructor callback. Optional. * @param pfnDtor Object destructor callback. Optional. * @param pvUser User argument for the two callbacks. * @param fFlags Flags reserved for future use. Must be zero. */ RTDECL(int) RTMemCacheCreate(PRTMEMCACHE phMemCache, size_t cbObject, size_t cbAlignment, uint32_t cMaxObjects, PFNMEMCACHECTOR pfnCtor, PFNMEMCACHEDTOR pfnDtor, void *pvUser, uint32_t fFlags); /** * Destroy a cache destroying and freeing allocated memory. * * @returns IPRT status code. * @param hMemCache The cache handle. NIL is quietly (VINF_SUCCESS) * ignored. */ RTDECL(int) RTMemCacheDestroy(RTMEMCACHE hMemCache); /** * Allocate an object. * * @returns Pointer to the allocated cache object. * @param hMemCache The cache handle. */ RTDECL(void *) RTMemCacheAlloc(RTMEMCACHE hMemCache); /** * Allocate an object and return a proper status code. * * @returns IPRT status code. * @retval VERR_MEM_CACHE_MAX_SIZE if we've reached maximum size (see * RTMemCacheCreate). * @retval VERR_NO_MEMORY if we failed to allocate more memory for the cache. * * @param hMemCache The cache handle. * @param ppvObj Where to return the object. */ RTDECL(int) RTMemCacheAllocEx(RTMEMCACHE hMemCache, void **ppvObj); /** * Free an object previously returned by RTMemCacheAlloc or RTMemCacheAllocEx. * * @param hMemCache The cache handle. * @param pvObj The object to free. NULL is fine. */ RTDECL(void) RTMemCacheFree(RTMEMCACHE hMemCache, void *pvObj); /** @} */ RT_C_DECLS_END #endif /* !IPRT_INCLUDED_memcache_h */